1. Field of the Invention
This invention relates to the field of solid state electronics and particularly to the field of solid state photodiodes for detecting infrared energy.
2. Description of the Prior Art
The performance of photodiodes is reduced by leakage current which can be considered to be a parastic current flowing in parallel with the desirable photocurrent. Leakage current is made up of bulk current and excess current (surface current) and the amount and contribution of these currents to the total leakage current varies with temperature as described in INVESTIGATIONS OF LEAKAGE CHARACTERISTICS OF PbSnTe-PbTe INVERTED HETEROSTRUCTURE DIODES by Wang, Kalisher, Tracy, Clarke, and Longo, SOLID STATE ELECTRONICS, 1978, vol. 21, pp. 625-632.
Photodiodes for 8-14 .mu.m infrared detection have been fabricated using PbSnTe semiconducting material. One such photodiode is described in U.S. Pat. No. 4,021,836. Although such prior art photodiodes are capable of high performance, there is a continuing need to decrease the leakage and improve the efficiency and performance of photodiodes.